Bangkok - Thailand's share prices plummeted 9.6 per cent Friday, prompting regulators to close the market for 30 minutes after midday trading when share values had dropped more than 10 per cent.

The Stock Exchange of Thailand (SET) index ended at 451.96, down 48.03 points, or 9.6 per cent.

After the midday break, the index slipped to 449.91, down 50.08 points, or 10.02 per cent, prompting authorities to close trading for half an hour in keeping with the bourse's regulations.

The bourse resumed trading in the afternoon.

The SET last used a circuit breaker in December, 2006, after the government placed capital controls, triggering a record plunge in share prices.

"The major factor at play here was the crash on the Wall Street, but Thailand's political instability helped bring things down further," said Phuwadol Larpudomsak, an analyst at Asia Plus Securities.

Thailand's political scene has been shaken by an ongoing confrontation between the government and the anti-government People's Alliance for Democracy, which has been staging protests against the administration for the past six months and has occupied Government House, the seat of the executive body, since August 26.

The impasse has raised concerns about the military staging a coup, as they did in September 19, 2006, to topple the government of Thaksin Shinawatra. (dpa)